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You can run Windows XP from an external USB hard drive

Although Microsoft says it's not possible to run Windows XP from an external (USB) hard drive, Ngine Software has created a guide to building an installation of Windows XP that can be booted from an external USB hard drive.

Time and again people ask me if it's possible to run Windows XP from an external (USB) hard drive. Common sense...

tells me this isn't possible, and Microsoft's own word on the subject is a flat no -- that a USB storage device cannot be the primary means of storage. At least not until standards in computing change.

But some people just don't take no for an answer. Certainly not Emanuel Schleussinger and his cronies at Ngine software, who have created a guide to building an installation of Windows XP that can be booted from a USB hard drive.

Last revised in March 2006, the process has been tested against a number of different configurations and seems to work transparently, although it's definitely not a supported configuration and should only be used by those brave enough to try it! The site also maintains a forum for feedback and success/failure stories with this technique. (One such post describes how to modify a current installation to run from an external drive.)

The process involves extracting several files from the Windows XP installation CD, modifying them, and reburning the install CD with the modified files. The files to be edited are mostly .INF files from the installation, and they must be edited exactly as described or the process will not work. (Some of the edited entries in the .INF files use German prompts, but it should be fairly easy to find their English counterparts, since the file names themselves don't change. Also, during the installation process with the modified XP disc, you may get a warning about the USB drivers not being certified; you can safely agree to installing them.

Machine must supports booting from USB device

Still on Windows XP?

If your organization has considered an OS upgrade but hasn’t pulled the trigger yet, check out this Windows 7 migration guide.

One caveat: This only works on a computer that supports booting from a USB device. Many machines made today still will not do this (I have a Sony VAIO notebook that doesn't boot from USB). But the authors have included instructions to help you discern if this is the case, and whether or not the device you're using is bootable as well. Many boot-supported devices will only work when connected directly to the PC, not when attached via a hub, so keep this in mind.

Finally, one other issue: Since Windows cannot create a page file on a USB device, it will warn you that no page file exists when Windows starts up. If you have a fixed disk installed in the system in question, you can probably set up a page file manually on that drive. Running Windows without a page file can have unpredictable results in the long run (I've experienced them myself), so it's in your best interest to set up a page file on a fixed drive whenever you can.

While running XP from a USB drive is a power-user thing, I can think of a scenario where an admin might want to have this capability, for instance, if they wanted to have a full copy of XP on a non-internal drive for the sake of system recovery. It would be more powerful than a live recovery CD (you could install full copies of software on it). But I can also think of a drawback: Because of Product Activation, it would only work well on the system it was originally configured to run on (provided you haven't just blown past activation entirely and are just using it in the 30- to 60-day trial mode).

Another possible use is if you had a system with a defective or problematic IDE controller, but still wanted to use it to run Windows somehow.

About the author: Serdar Yegulalp is editor of the Windows Insight, (formerly the Windows Power Users Newsletter), a blog site devoted to hints, tips, tricks and news for users and administrators of Windows NT, Windows 2000, Windows XP, Windows Server 2003 and Vista. He has more than 12 years of Windows experience under his belt, and contributes regularly to and

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